TW201838304A - Switch mode power system, inductor current sensing device and method thereof, slpoe sensing device and method thereof - Google Patents

Abstract

Aspects of the present disclosure describe a SMPS system, comprising a SMPS and an inductor current sensing device. The SMPS comprise a high-side (HS) switch and a low-side (LS) switch coupled in series and an output filter including an inductor and a capacitor coupled to a switch node formed by the HS and LS switches. An inductor current is supplied by the inductor to a load. The inductor current sensing device coupled across the LS switch has a first input configured to receive a node signal indicating a voltage level at the switch node, a second input configured to receive an input voltage of the system and a third input configured to receive an output voltage of the system. The inductor current sensing device is configured to obtain a first constant DC slope information, a second constant DC slope information and a valley current information based on the first input, second and third inputs, and generate an output signal based on the first constant DC slope information, the second constant DC slope information and the valley current information. The output signal has a triangular waveform including a rising slope and a falling slope proportional to rising and falling slopes of the inductor current.

Description

Switching power supply system, inductive current sensing element and method, slope sensing element and method thereof

The present invention relates to an integrated circuit, and more particularly to a current sensing element used in a Switch Mode Power Supply (SMPS).

Integrated circuits such as microprocessors and storage elements include multiple metal-oxide-semiconductor field effect transistors (MOSFETs) that provide basic switching functions for configuring logic gates, data storage, power switches, and other components. In one application, MOSFETs have been widely used in switched-mode power supplies (SMPS) because of their power and thermal effectiveness. In addition to MOSFET switches, SMPS also includes energy-saving components such as inductors or capacitors.

Power is a key component in any electronic component, and its performance can affect power efficiency, production safety, and product performance. Therefore, for the power supply, a power monitoring system must be included to monitor and / or modulate its output. Power supply modulation usually includes output voltage or current feedback. Since many SMPS systems (that is, SMPS includes power monitoring or modulation functions) are modulated using current modules, the key to this system is to obtain the actual current information.

Current computing applications require SMPS systems to operate at higher frequencies to increase bandwidth. These applications also require SMPS systems to have smaller manufacturing factors and lower costs. SMPS system manufacturers have responded to these needs by using small inductors and capacitors. In addition, there is a tendency to reduce the operating voltage of SMPS systems (such as step-down DC-DC converters) for higher speed operation and better energy savings. As a result, the voltage ratio (V _IN / V _OUT ) between the input voltage and the output voltage increases, and the energy saving period (ie, the on-time period D) becomes shorter. Due to the high switching frequency, short on-time period, and noise generated when the switch is turned on and off in such a system, it is a challenge to truly sense the current information in such a system.

It is against this background that embodiments of the present invention are proposed.

The purpose of the present invention is to propose a full-time inductor current monitoring method by sensing a low-end switch to improve one or more problems in the prior art.

One aspect of the present invention is to propose a switching power supply system including: a switching power supply including a high-end switch and a low-end switch coupled in series; an output filter including an inductor and a capacitor coupled to High-end and low-end switches are connected in series, where the inductor current is provided by the inductor to the load; and an inductor current sensing element is coupled to the low-side switch; the inductor current sensing element has a first input terminal for The receiving node signal indicates the voltage level at the switching node; a second input terminal is used to receive the input voltage V _{IN of the} system; and a third input terminal is used to receive the output voltage V _{OUT of the} system; where the inductor current sense The measuring device is configured to receive the first constant DC slope information, the second constant DC slope information, and the valley current information according to the first input terminal, the second input terminal, and the third input terminal. Two constant DC slope information and valley current information to generate an output signal, where the output signal has A triangular waveform, including a rising slope and a falling slope, proportional to the rising and falling slope of the inductor current.

The inductor current sensing element includes: a current sensing circuit that generates a sensing current according to the node information, wherein the sensing current includes a first current slope and a minimum current value; a slope sensing circuit coupled to the current sensing On the circuit; the slope sensing circuit has a first input terminal for receiving a sensing current from the current sensing circuit, wherein the slope sensing circuit is used to convert a first current slope in the sensing current to a first constant DC Slope information; an arithmetic circuit coupled to the slope sensing circuit; the arithmetic circuit has a first input terminal for receiving a first constant DC slope information from the slope sensing circuit; a second input terminal for receiving input A voltage V _IN ; and a third input terminal for receiving the output voltage V _OUT ; wherein the arithmetic circuit is used for generating a second constant DC slope information according to the first, second and third input terminals; and a current slope synthesis circuit , Coupled to the arithmetic circuit and the efficiency sensing circuit; the current slope synthesis circuit has a first input terminal for receiving the first Constant DC slope information; a second input terminal for receiving a second constant DC slope message; and a third input terminal for receiving a control signal; wherein a current slope synthesis circuit is configured to combine the first and second constant DC slope signals The information is integrated to generate a composite signal according to the control signal. The composite signal has a triangular waveform, including a rising slope when the control signal is in a first state and a falling slope when the control signal is in a second state opposite to the first state. The rising and falling slopes of the composite signal are proportional to the rising and falling slopes of the inductor current, respectively.

The inductor current sensing element further includes a valley current sensing circuit coupled to the current sensing circuit. The valley current sensing circuit has a first input terminal for receiving a sensing current from the current sensing circuit. The valley current sensing circuit is used to convert the smallest current value of the sensed current into a valley current message.

Among them, each of the slope sensing circuit and the valley current sensing circuit has a sample and hold circuit.

The inductor current sensing element further includes an addition circuit coupled to the current slope synthesis circuit and the valley current sensing circuit. The addition circuit is configured to generate a combined signal by combining the synthesized signal and the valley current information.

The inductive current sensing element further includes a buffer driver coupled to the addition circuit. The buffer driver is configured to drive a combined signal from the addition circuit to generate an output signal.

The arithmetic circuit is configured to generate a second constant DC slope message by multiplying the first constant DC slope message by ((V _IN -V _OUT ) / V _OUT ).

Another aspect of the present invention is to provide an inductive current sensing element for detecting an inductive current in a switching power supply, wherein the switching power supply has a high-end switch and a low-end switch connected in series, and an output filter. The output filter includes an inductor and a capacitor, which are coupled to the switch node through the high-side and low-side switches, where the inductor current is provided to the load by the inductor; the inductor current sensing element includes: a current sensing circuit, coupled to the low-side On the switch; a current sensing circuit is configured to sense the current on the low-end switch and generate a sensing current, wherein the sensing current includes a first current slope and a minimum current value; a slope sensing circuit is coupled to the current sensing On the circuit; the slope sensing circuit has a first input terminal for receiving a sensing current from the current sensing circuit, wherein a slope sensing circuit is configured to convert a first current slope in the sensing current into a first constant DC slope information; an arithmetic circuit coupled to the slope sensing circuit; the arithmetic circuit has a first input For receiving a message from a first constant current slope slope sensing circuit; a second input terminal for receiving an input of the SMPS voltage V _IN; a third input terminal for receiving the SMPS output voltage V _OUT; wherein The operation circuit is configured to generate a second constant DC slope information according to the first, second and third input terminals; and a current slope synthesis circuit is coupled to the operation circuit and the slope sensing circuit; the current slope synthesis circuit has a first An input terminal for receiving a first constant DC slope message; a second input terminal for receiving a second constant DC slope message; and a third input terminal for receiving a control signal. A current slope buffer circuit is configured by The control signal integrates the first and second constant DC slope information. The synthesized signal has a triangular waveform, including the rising slope when the control signal is in the first state and the fall when the control signal is in the second state opposite to the first state. Slope, where the rising and falling slopes of the composite signal are proportional to the rising and falling slopes of the inductor current, respectively.

The inductive current sensing element further includes a valley current sensing circuit coupled to the path of the current trench. The valley sensing circuit has a first input terminal for receiving a sensing current from the current sensing circuit. A valley current sensing circuit is configured to convert the smallest current value of the sensed current into a valley current message.

Among them, each of the slope sensing circuit and the valley current sensing circuit has a sample and hold circuit.

The inductor current sensing element further includes an addition circuit coupled to the current slope synthesis circuit and the valley current sensing circuit. The addition circuit is configured to generate a combined signal by combining the synthesized signal and the valley current information.

The inductor current sensing element further includes a buffer driver coupled to the addition circuit. The buffer driver is configured to drive a combined signal from the addition circuit to generate an output signal. The output signal has a triangular waveform including a rising slope and a falling The slope is proportional to the rising and falling slope of the inductor current.

Wherein, an arithmetic circuit is configured to generate a second constant DC slope message by multiplying the first constant DC slope message by ((V _IN -V _OUT ) / V _OUT ).

Another aspect of the present invention is to provide a method for sensing an inductor current in a switching power supply, wherein the switching power supply has a high-end switch and a low-end switch connected in series; and an output filter, the output filter includes An inductor and a capacitor are coupled to the switching node formed by the high-side and low-side switches, wherein the inductor current is provided to the load by the inductor; the method includes: generating a sensing current by sensing the current on the low-side switch, where The sensing current includes a first current slope and a minimum current value; converting the first current slope in the sensing current into a first constant DC slope message; and according to the first constant DC slope message, the input voltage V _{IN of the} switching power supply and The output voltage V _{OUT of the} switching power supply generates a second constant DC slope information; and by integrating the first and second constant DC slope information according to the control signal, a composite signal is generated, where the composite signal has a triangular waveform, including Rising slope in the first state and when the control signal is opposite to the first state The falling slope in the second state, where the rising and falling slopes of the composite signal are proportional to the rising and falling slopes of the inductor current, respectively.

The method further includes converting the minimum current value in the sensing current into a valley current message.

Wherein, converting the minimum current value in the sensing current into a valley current message includes sampling and maintaining the minimum current value according to the trigger signal.

The converting the first current slope in the sensing current into the first constant DC slope information includes sampling and holding the first current slope according to the trigger signal.

Among them, it further includes generating a combined signal by combining the synthesized signal and the valley current information.

The generating of the second constant DC slope information includes multiplying the first constant DC slope information by ((V _IN -V _OUT ) / V _OUT ).

Another aspect of the present invention is to provide a slope sensing element for sensing the slope of an input signal and providing an output signal proportional to the input signal. The slope sensing element includes a differentiator having an input terminal, and For receiving an input signal with a triangular waveform with at least one slope; a differentiator is configured to use the first capacitor to generate a differential signal through the differential input signal; a sample and hold circuit has a first input terminal for receiving a differential Signal; and a second input terminal for receiving a trigger signal; wherein a sample and hold circuit is configured to convert the differential signal into a constant DC slope message by sampling and holding the differential signal when the trigger signal is turned on; and an integrator, It has an input terminal for receiving a constant DC slope message; the integrator is used to receive the output signal, and a second capacitor is used, and the waveform of the output signal is proportional to the waveform of the input signal.

The differentiator includes an operational tutor amplifier.

An integrator is configured to generate an output signal through charging and discharging of the second capacitor according to the constant DC slope information.

In a preferred embodiment of the present invention, the slope sensing element further includes an arithmetic circuit coupled to the sample and hold circuit, and the arithmetic circuit is configured to generate a second constant DC slope information according to the constant DC slope information.

The integrator has a second input terminal for receiving a second constant DC slope. The integrator is configured to generate an output signal by using a second capacitor to integrate the constant DC slope information and the second constant DC slope information.

The integrator includes two switches controlled by a control signal. When the control signal is in the first state, the first switch is turned on and the second switch is turned off. When the control signal is in the second state opposite to the first state, , The first switch is turned off, and the second switch is turned on; wherein when the control signal is in the first state, the second capacitor is discharged according to the constant DC slope message; when the control signal is in the second state, according to the second constant DC slope message The second capacitor is charged.

In another preferred embodiment of the present invention, the slope sensing element further includes a second differentiator that uses the first capacitor to generate a second differential signal; and a second sample and hold circuit that converts the second differential signal into Second constant DC slope message.

The integrator has a second input terminal for receiving a second constant DC slope; the integrator is configured to use the second capacitor to generate an output signal to integrate the constant DC slope information and the second constant DC slope information.

The integrator includes two switches controlled by a control signal. When the control signal is in the first state, the first switch is turned on and the second switch is turned off. When the control signal is in the second state opposite to the first state, , The first switch is turned off, and the second switch is turned on; wherein when the control signal is in the first state, the second capacitor is discharged according to the constant DC slope message; when the control signal is in the second state, according to the second constant DC slope message The second capacitor is charged.

Another aspect of the present invention is to provide a method for sensing the slope of an input signal and providing an output signal proportional to the input signal. The method includes: differentiating an input signal having a triangular waveform with at least one slope. A capacitor generates a differential signal; when the trigger signal is turned on, the differential signal is sampled and held to convert the differential signal into a constant DC slope message; a second capacitor is used to generate an output signal and integrate the constant DC slope message, where the output signal The waveform is proportional to the waveform of the input signal.

Among them, generating an output signal includes charging and discharging the second capacitor according to a constant DC slope.

The method further includes generating a second constant DC slope information according to the constant DC slope information.

Wherein, using the second capacitor to generate an output signal includes discharging the second capacitor according to a constant DC slope message when the control signal is in the first state; and when the control signal is in the second state opposite to the first state, according to A second constant DC slope message charges the second capacitor.

The method further includes using the first capacitor to generate a second differential signal, and converting the second differential signal into a second constant DC slope information.

Wherein, using the second capacitor to generate an output signal includes discharging the second capacitor according to a constant DC slope message when the control signal is in the first state; and when the control signal is in the second state opposite to the first state, according to A second constant DC slope message charges the second capacitor.

These features and advantages of the present invention will undoubtedly be obvious to those skilled in the art after reading the embodiments detailed below and referring to various drawings.

In the following description, signal-related variables are used or referenced, such as V _IN , V _OUT , i _L. It should be noted that the large signal is a DC signal (or an AC signal at a point in time), which is one or more orders of magnitude larger than the small signal. It is used to analyze circuits containing non-linear parts and calculate the operating points of these parts. (bias). Large-signal DC quantities are represented by capital letters with a capital letter. Small semaphores are represented by lower case letters with a lower case letter. An example of a small signal is an AC signal superimposed on a circuit containing a large signal. Totals containing small and large signals are indicated by lowercase letters with a capital letter.

introduction

As mentioned above, since the system needs current information for power modulation, actual current monitoring is critical in a current mode operating system. Various design schemes have been proposed in SMPS for inductor current sensing / monitoring to monitor its current information.

Fig. 1 (a) is a conventional SMPS with a current sensing element. The SMPS system 100 is a step-down DC-DC converter, including power switching elements M1-D1, M2-D2, connected in series to an input voltage source. The power switching elements M1-D1 are coupled to the voltage source VIN, and the power switching elements M2-D2 are grounded to GND. The power switching elements M1-D1 are also referred to as high-side (HS) switches, and the power switching elements M2-D2 are also referred to as low-side (LS) switches. The output filter includes an inductor L1 and a capacitor C1, which are connected to a node 105 (ie, a phase node or a switching node). The node 105 is made of a pair of HS and LS switches to provide an output voltage V _OUT to the load. The inductor L1 has a parasitic DC resistance R _DC . Through the HS and LS switches, the output inductor L1 is switched alternately, and one end is connected to the input voltage V _IN and the ground GND. Therefore, the controller (not shown in Figure 1 (a)) controls the on and off actions of the HS and LS switches to generate an output voltage V _OUT that is lower than the input voltage level V _IN . The controller turns on and off the HS and LS switches at the switching frequency fsw. The output voltage V _OUT is buffered on the capacitor C1. A load (not shown in FIG. 1 (a)) can be coupled to the output node 107, and the current i _L can be provided to the load through the inductor L1. For a current mode operating system, the inductor current i _L must be obtained or sensed for power supply modulation.

Regarding inductive current sensing, the system 100 has a low-pass RC sensing element. The low-pass RC sensing element is connected in series by a resistor Rs and a capacitor Cs. The RC sensing element is connected in parallel with the inductor L1. The inductor L1 has a parasitic DC resistance R _DC . The RC sensing element filters the voltage on the inductor L1 and senses the current through the parasitic DC resistance R _{DC of the} inductor L1. Generally, the sensed voltage V _CS on the capacitor Cs is expressed as a sensed output voltage. As shown in FIG. 1 (b), the waveform of the sensing voltage V _CS follows the waveform of the inductor current i _L. Therefore, the current i _L sensed by the inductor can be achieved by obtaining the sensing voltage V _CS .

Generally, in order to make the DC-DC converter have good performance, the time constant (L1 / R _DC ) of the inductor L1 should be much larger than the switching time (1 / fsw). In addition, the time constant (Rs / Cs) of the low-pass RC sensing element must be the same as the time constant of inductor L1 for real sensing, as shown in the following formula (1): (1).

However, the above RC sensing method also has some disadvantages. First, due to the parasitic resistance R _{DC of the} inductor L1, the system has poor accuracy or power loss. According to equation (1), the parasitic resistance R _DC should be small in order to work at high frequencies. The smaller parasitic resistance R _DC also helps reduce power loss and is conducive to energy efficiency. However, when the parasitic resistance R _DC is small, its voltage ripple is also small, and it becomes difficult to recognize the falling message. That is, the voltage V _CS sensed on the capacitor Cs is too small to be identified. This problem is exacerbated by light loads with very low currents. Although the large parasitic resistance R _{DC is} helpful for identifying falling information and accurately sensing the current slope, it will cause a large power loss.

In addition, the components used in traditional RC sensing methods are sensitive to temperature. Replacing these components reduces costs and still cannot guarantee accuracy at light loads. The value of the parasitic resistance R _DC is assigned. Therefore, it is impossible to measure the parasitic resistance R _DC and there is no way to compensate for it. The inductance current information obtained based on the parasitic resistance R _DC cannot be accurate.

Inductive current sensing element / method

Various aspects of the present invention provide an inductive current sensing element and / or method for a SMPS system, and obtain an inductive current only by sensing information of an LS switch. According to various aspects of the present invention, the inductor current sensing information is divided into rising and falling current slope information and average current information. The "average current" here refers to the DC value of the inductor current. Figure 1 (b) shows the inductor current waveform, which consists of a DC (average) part and an AC (triangle). The AC part is characterized by a maximum current iL_peak (iL_peak) and a minimum current iL_valley (iL_valley). In this case, the average current is iL (average) = iL_valley value + ΔiL / 2, where ΔiL = iL_peak value-iL_valley value. The sensing and processing of the messages are performed separately, combined into one output signal, and reported to the controller for modulation. According to various aspects of the present invention, depending on the application, the sensing method may be configured by a controller IC, a driver IC, or a separate element.

According to various aspects of the invention, a SMPS system includes a SMPS and an inductive current sensing element. SMPS includes an HS switch and an LS switch in series, an output filter containing an inductor and a capacitor coupled to a switch node, and the switch node is composed of HS and LS switches. Inductive current is provided to the load by the inductor. The inductive current sensing element on the LS switch has a first input terminal configured to receive a node signal indicating a voltage level at the switching node, a second input terminal configured to receive an input voltage of the system, and a third configured terminal Input to receive the output voltage of the system. The inductor current sensing element is configured to obtain the first constant DC slope information, the second constant DC slope information, and the valley current information according to the first input terminal, the second and third input terminals, and according to the first constant DC slope information, The second constant current message and the valley current message generate an output signal. The output signal has a triangular waveform, including a rising slope and a falling slope, which are proportional to the rising and falling slopes of the inductor current.

FIG. 2 is a schematic structural diagram of an SMPS system with an inductive current sensing element according to various aspects of the present invention. In this embodiment, the SMPS system 200 includes a step-down DC-DC converter, and an inductive current sensing element 300 is coupled to the converter. In other embodiments, the power supply in the SMPS system 200 may be a step-up DC-DC converter, or a step-down and step-up DC-DC converter, or any other SMPS. Similar to FIG. 1 (a), the DC-DC converter in the SMPS system shown in FIG. 2 includes power switching elements M1-D1, M2-D2, and is connected in series to an input voltage source. The power switching elements M1-D1 are coupled to a voltage source V _IN , and the power switching elements M2-D2 are grounded to GND. The power switching elements M1-D1 are also referred to as high-end (HS) switches, and the power switching elements M2-D2 are also referred to as low-end (LS) switches. The output filter includes an inductor L1 and a capacitor C1, which are connected to ground 105 (ie, a phase node or a switching node). Node 105 is composed of a pair of HS switches and LS switches, and is used to provide an output voltage V _OUT for the load. The output voltage V _OUT is buffered on the capacitor C1. A load (not shown in Figure 2) can be coupled to the output node 107, and the current i _L can be provided to the load by the inductor L1.

HS and LS switches are controlled by pulse width modulation (PWM) signals, which are generated by the controller (not shown). In one embodiment, the HS switch is controlled by a PWM signal, and the LS switch is controlled by a complementary mode of the PWM signal, or a NOT (NOT) signal of the PWM signal. Therefore, when the PWM signal is in the first logic state (such as a high logic signal) and the non-signal of the PWM signal is in a low logic signal, the HS switch is turned on (that is, MOSFET M1 is turned on) and the LS switch is turned off (that is, MOSFET M2 is turned off) ). At this time, the current starts from the input node and flows to the inductor L1 through the HS switch. The inductance current i _L flowing through the inductor L1 is equal to the HS current i _HS flowing through the HS switch. When the PWM signal is in the second logic state (such as a low logic signal) and the non-signal of the PWM signal is in a high logic signal, the HS switch is turned off (ie, MOSFET M1 is turned off) and the LS switch is turned on (ie, MOSFET M2 is turned on). As shown in Figure 2, current flows from ground through the LS switch to inductor L1. During this time, the inductor current i _L is equal to the LS current i _LS flowing through the LS switch (M2 or D2). Because the on-time of the HS switch is short, sensing HS current information is possible, but very difficult. Various aspects of the present invention provide a method capable of sensing an inductor current only by sensing a message of an LS switch. Therefore, when the HS switch is on and the LS switch is off, according to the sensing message of the LS switch, an HS current message equal to the inductor current can be generated or simulated. When the HS switch is turned off and the LS switch is turned on, the inductor current is the sensed current message of the LS switch.

In order to sense the LS current information (that is, the source-to-drain current of the MOSFET M2), the drain-to-source voltage V _DS and the on-resistance R _{DS_ON of the} MOSFET M2 must first be obtained. The drain-to-source voltage V _{DS of the} MOSFET M2 is equal to the falling voltage of the inductor current i _L. Therefore, the drain voltage V _DS includes the current information of the inductor L1. As shown in FIG. 2, the inductive current sensing element 300 is coupled to the source and the drain of the LS switch, and receives the drain voltage V _DS as one of the input terminals of the inductive current sensing element 300. In one embodiment, the drain-source voltage V _DS may be obtained from the voltage V _LX because the voltage V _DS is equal to the difference between the voltage V _LX and the ground GND. In addition, the information of the input voltage V _IN and the output voltage V _OUT is also provided to the inductor current sensing element 300. In one embodiment, the message of the output voltage V _OUT can be replaced with the filtered (or average) voltage V _LX , because the filtered voltage V _{LX is} almost the same as the output voltage V _OUT .

FIG. 3 is a schematic structural diagram of the inductive current sensing element 300. The inductive current sensing element 300 includes an LS current sensing circuit 310, a slope sensing circuit 320, a valley current sensing circuit 330, an operation circuit 340, a current slope synthesis circuit 350, and a buffer driver 360. The LS current sensing circuit 310 receives the source voltage V _DS from the LS switch and converts it into a sensing current signal Iss. The sensed current signal Iss includes information of the current slope (for example, from ΔV _DS / Δt) and a minimum current value (for example, the minimum voltage from the drain voltage V _DS ). Then, the sensing current signal Iss from the LS current sensing circuit 310 is provided to the slope sensing circuit 320 and the valley current sensing circuit 330.

In the slope sensing circuit 320, current slope information of the sensed current signal Iss is converted into constant current slope information. In one embodiment, the slope sensing circuit 320 includes a sample and hold circuit (not shown in FIG. 3) to generate a constant DC message with an LS current slope (I _{LS_SLP} ). The valley current sensing circuit 330 converts the minimum current value in the sense current signal Iss into a valley circuit message. In one embodiment, the valley current sensing circuit 330 includes a sample and hold circuit (not shown in FIG. 3) to generate a constant DC message of the LS valley current (I _{S_VALLEY} ).

The arithmetic circuit 340 receives the LS current slope information I _{LS_SLP} from the slope sensing circuit 320, the input voltage V _IN and the output voltage V _OUT as input terminals. Based on these inputs, the arithmetic circuit 340 is configured to calculate the HS current slope information based on the relationship between the HS current slope and LS is the current slope, as shown in the following formula (2): (2).

For the arithmetic circuit 340, equation (2) can be converted into the following equation (3) to calculate the HS current slope information: (3);

Among them, Δi _{L_FALL} and Δi _{L_RISE} can be replaced by LS current slope information I _{LS_SLP} and HS current slope information I _{HS_SLP, respectively} . Therefore, the HS current slope information I _{HS_SLP} can be multiplied by the LS current slope information I _{LS_SLP} by (V _IN / V _OUT ), and then subtracted from the LS current slope information I _{LS_SLP} . In one embodiment, the operation circuit 340 includes a circuit (such as an operational amplifier) for performing a numerical operation, multiplying the LS current slope information I _{LS_SLP} by (V _IN / V _OUT ), and then subtracting the LS current slope information I _{LS_SLP} . In another embodiment, the operation circuit 340 is configured to perform a numerical operation, and the LS current slope information I _{LS_SLP is} multiplied by (V _IN / V _OUT ); and the subtraction circuit 342 is separated from the operation circuit 340 and is used for removing the Output minus LS current slope message I _{LS_SLP} .

Once the LS current slope information I _{LS_SLP} and the HS current slope information I _{HS_SLP are obtained} , the current slope synthesis circuit 350 integrates the information according to the PWM signal and generates a synthesized signal i _SLP . When the PWM signal is in a high state, the synthesized signal i _SLP is a triangular waveform with a rising slope, and when the PWM signal is in a low state, it is a falling slope. The rising slope is based on the HS current slope message I _{HS_SLP} , and the falling slope is based on the LS current slope message I _{LS_SLP} . The rising and falling slopes of the composite signal i _SLP are proportional to the rising and falling slopes of the inductor current i _L , as shown in the following formula (4): (4);

Where (1 / K1) is the conversion gain of the LS current sensing circuit 310, and (1 / K2) is the conversion gain of the current slope synthesis circuit 350. It should be noted that the valley current message I _{S_VALLEY} also has the same conversion gain, as shown in the following formula (5): (5).

The adding circuit 352 combines the synthesized signal i _SLP from the current slope synthesizing circuit 350 and the valley current message I _{S_VALLEY} from the valley current sensing circuit 330 to generate a combined signal. The buffer driver 360 then drives the combined signal and outputs the signal I _MON as shown in the following formula (6). The signal I _MON can be input to the switch controller, and the switch controller controls the on and off of the HS and LS switches; (6).

According to equation (6), the signal I _MON can represent the inductance current i _L of the inductor L1. In one embodiment, the buffer driver 360 may convert the signal I _MON into a voltage signal V _MON by multiplying the signal I _MON by a resistor R _MON . In this embodiment, an output waveform can be generated according to the following formula.

When (0 <t <DT), (7a)

When (DT <t <T), (7b)

Among them, PWM = H means that the PWM signal is in a high state (that is, 0 <t <DT), and PWM = L means that the PWM signal is in a low state (that is, DT <t <T). The valley current message V _{S_VALLEY} is the valley value. The previous (n-1) message of the current message, the slope message △ V _MON is the previous (n-1) slope message. Current (n) V _MON spend a message (n-1) a _(n-1) V S_VALLEY and the △ V _MON calculation.

FIG. 4 shows a signal waveform of a signal in the inductor current sensing element 300 shown in FIG. 3. The signal 402 is a waveform of the inductor current i _L in the DC-DC converter shown in FIG. 2. The signal 404 is the LX node voltage signal V _LX . During the rising and falling edges of the PWM signal 406, the large voltage drop in the signal 404 is caused by the forward operation of the LS diode D2 during the dead time, and the forward operation turns off the HS and LS switches. Signal 406 is a PWM signal that controls the HS and LS switches. The signal 408 is a signal LXf, which indicates the on-time of the LS switch. The signal 410 is a signal LXfd, which represents a sensing time, and the leading edge turn-off time td_led is subtracted from the signal LXf. The signals 412 and 414 are trigger signals of the corresponding sample and hold circuits in the slope sensing circuit 320 and the valley current sensing circuit 330 (ie, SH1 and SH2 shown in FIG. 3). The signal 416 is the signal Iss. When the signal 410 is in the high state, it is from the LS current sensing circuit 310. When the corresponding trigger signals 412 and 414 are turned on, the falling slope message I _LS-SLP and the valley current message I _{S_VALLEY} as shown in the waveform 418 in FIG. 4 are sampled and held respectively. The sample and hold operation usually takes place as late as possible at the end of the PWM time to obtain a true message.

Based on the falling slope information I _{LS_SLP} and the input voltage V _IN and output voltage V _OUT and the arithmetic circuit 340, the rising slope information I _HS-SLP shown in the signal 420 in FIG. 4 is calculated. As shown in FIG. 4, the signal 418 (ie, the rising slope signal I _{LS_SLP} ) and the signal 420 (ie, the rising slope signal I _HS-SLP ) are constant DC currents. The signals 418 and 420 are combined by the current slope synthesis circuit 350. The current slope synthesis circuit 350 combines the information according to the PWM signal 406, and generates a synthesized signal 422 (i _SLP ). When the PWM signal 406 is in a high state, the synthesized signal 422 (i _SLP ) is a triangular waveform containing a rising slope. When the PWM signal is in a low state, the synthesized signal 422 (i _SLP ) contains a falling slope. The rising slope is based on the HS current slope information 420 (I _{HS_SLP} ), and the falling slope is based on the LS current slope information 418 (I _{LS_SLP} ). In one embodiment, the triangular waveform I _SLP can be moved by a known DC offset I _REF . The signal 424 is a final waveform I _MON including a signal 422 (i _SLP ) and a valley current message (I _{S_VALLEY} ). Since the signal I _MON can represent the inductance current i _L of the inductor L1, it can be seen from FIG. 1 (b) that, for example, the inductance current iL can be obtained by using equation (6) and iL = iL_valley + ΔiL.

Current slope sensing method / component

Inductive current sensing elements, such as the sensing element 300 shown in FIG. 3, generally need to sense the current slope. Regarding slope sensing, traditional methods used by DC-DC converters (such as the step-down DC-DC converter 500 shown in Figure 5 (a)) use analog-to-digital converters (ADCs) and digital-to-analog converters. (DAC). When the LS switch M2 is turned on, the voltage V _LX shown in FIG. 5 (b) is the voltage at the LX node. It should be noted that there are two dead time when the diodes D1 and D2 work. When the HS switch M1 and the LS switch M2 are in the transition time, cross conduction is prevented. Except for the diode operating time, the slope of the voltage V _LX is proportional to the slope of the inductor current. Therefore, the conventional current sensing element / method 510 as shown in FIG. 5 (c) uses the ADC 512, the digital operator 520, and the DAC 530 to sense the current slope based on the voltage V _LX . However, the use of components such as ADCs and DACs in current sensing components is relatively expensive and takes up a lot of space on the components, thus increasing the overall design and cost.

According to various aspects of the present invention, FIGS. 6 (a) and 6 (b) illustrate a slope sensing element for sensing the slope of an input signal, and the capacitor is provided with the input signal through a predefined gain routing capacitor. Proportional output signal. According to various aspects of the present invention, the slope sensing element includes a differentiator, using a first capacitor to differentiate the input signal, a sample and hold circuit, converting the differential signal into a constant DC slope message, and configuring an integrator, using the first Two capacitors generate an output signal, and the waveform of the output signal is proportional to the input signal waveform. Various aspects of the present invention, together with FIGS. 6 (a) and 6 (b), can be arranged in the inductive current sensing element 300 shown in FIG. 3, especially the LS current sensing circuit 310 and the slope sensing circuit. 320 and a current slope synthesis circuit 350.

FIG. 6 (a) shows a structural diagram of the current slope sensing element 600. The current slope sensing element 600 includes a capacitor 610, a differentiator 620, a sample and hold circuit 630, an integrator 640, and a capacitor 650. FIG. 6 (b) shows a signal waveform of a signal in the current slope sensing element 600 shown in FIG. 6 (a).

The input voltage signal Vin (t) of the current slope sensing element 600 is a falling voltage, as shown in the following equation (8): (8);

Where i _L is the target inductor current and R _DS-ON is the on-resistance of the corresponding switch. In the example of the DC-DC converter shown in FIG. 2, the input voltage of the current slope sensing element 600 may be the voltage V _LX at the phase node, and R _DS-ON in equation (8) may be an LS switch (M2 ) On resistance.

The input signal Vin (t) is first differentiated by the capacitor 610 in the differentiator 620 and then multiplied by K1 of the first-order gain. Therefore, according to the following formula (9), the linear voltage slope is converted into a DC current value (Is) in the differentiator 620; (9).

Fig. 9 (a) shows an example of the differentiator 620, and shows the capacitor 610. The differentiator 900a shown in FIG. 9 (a) is a falling voltage slope sensing differentiator, wherein the input voltage (for example, voltage V _LX ) of the current slope sensing element 600 has a leading edge sawtooth waveform on its falling slope. Figure 9 (a) illustrates a rising voltage slope sensing differentiator, wherein the input voltage of the slope sensing element 600 has a trailing edge sawtooth waveform on its rising slope.

The differentiator 620 generates a current Is, as shown in FIG. 6 (b). The generated current Is has noise during the transition time. Then, the sample and hold circuit 630 is configured to obtain a steady-state slope information Is (n), as shown in FIG. 6 (b). In the sample and hold circuit 630, the signal Is is sampled and held as the n-th message of the steady state slope message Is (n). The n-th slope information Is (n) is integrated by the capacitor 650 and multiplied by the second-order gain 1 / K2 in the integrator 640. Therefore, according to the following formula, the DC current slope information Is (n) is converted into a voltage signal; (10).

Equation (9) and equation (10) can be converted into the following equation: (11);

Among them, when C1 = C2, Δvout = Δvin / (K1 × K2). Therefore, with a predefined gain of 1 / (K1 × K2), the output voltage slope is proportional to the input voltage slope. In one embodiment, the output voltage Vout (t) can be converted into a current message, for example, through an operational tutor amplifier, a resistor amplifier, or a resistor, and can be seen only by a specific, previously sensed valley information (ie, the first (N-1) valley values) horizontal displacement.

FIG. 7 (a) is an example of a current slope sensing element 700 configured in an inductive current sensing element such as element 300 in the SMPS system, such as the system 200 shown in FIG. 2 for sensing SMPS (eg, a drop DC-DC converter). FIG. 7 (b) shows a signal waveform in the current slope sensing element 700.

The input voltage V _LX is the voltage at the phase (or LX) node of the falling DC-DC converter. The input voltage V _LX is differentiated by a differentiator. The differentiator includes a capacitor 710 and an operational tutor amplifier 720 with a gain of 1 / K1. The switch SW1 is controlled by a signal Lxfd indicating the sensing time. The sensing time is equal to the on time of the LS switch, minus the leading edge blanking time. When the signal Lxfd becomes high (that is, during the time when the inductor current decreases), the switch SW1 is turned on. When the voltage V _LX starts to decrease with a stable slope, the capacitor 710 starts to charge the amplifier 720 through the current. As shown in FIG. 7 (a), the amplifier 720 modulates its converted input voltage equal to its unconverted input voltage, and the unconverted input voltage is grounded. The charging current of the capacitor 710 will reach a constant DC current level in a steady state. The linear voltage slope is converted into the DC current slope value I _{SLP_F} in the amplifier 720, as shown in the following formula: (12).

Then, the current slope information is sampled and held in the sample and hold circuit 730, and is converted into the current slope information I _{SLP_F} (n) in the n-th time. It is a constant value, as shown in Figure 7 (b). The current slope information I _{SLP_F} (n) is used in the rising slope operation circuit 735 and has a gain A2. The rising slope calculation circuit 735 calculates the rising current slope according to the following equation (13) according to the falling current slope information I _{SLP_F} (n); (13).

Using the information of the falling current slope I _{SLP_F} (n) and the rising current slope I _{SLP_R} (n), the switches SW2 and SW3 controlled by the PWM signal can help the capacitor 750 integrate the message. In one example, when the PWM signal is high, the switch SW2 is turned on and the switch SW3 is turned off. During this time, the capacitor 750 is charged by the rising current slope I _{SLP_R} (n). According to the following formula, the voltage V _{SEN_R} (n) is obtained: (14).

When the PWM signal is low, switch SW2 is turned off and switch SW3 is turned on. During this time, the capacitor 750 is discharged by the falling current slope I _{SLP_F} (n). According to the following formula (15), the voltage V _{SEN_F} (n) is obtained: (15).

After the valley voltage information V _{SEN_VALLEY is sensed} from the voltage V _LX , the final output voltage V _SEN (n) is obtained according to equations (16a) and (16b). When the PWM signal is in the low state: (if (A2-1) = 1 / K2) (16a)

When the PWM signal is high: (16b)

Among them, V _{SEN_VALLEY} (n-1) is the (n-1) th valley voltage information sensed from the voltage V _LX , and the on-time of DT and HS switch is the same. With a predefined gain (1 / (K1 × K2), the output voltage slope is proportional to the corresponding slope of the inductor current iL. Therefore, the output voltage V _SEN (n) (t) can represent the inductor current iL.

FIG. 8 illustrates another example of the current slope sensing element 800 configured in the SMPS system, such as the system 200 illustrated in FIG. 2, which is used to sense the inductor current in the SMPS (eg, a DC-DC converter). In FIG. 7, the current slope sensing element 700 calculates the HS rising current slope according to the sensed LS falling current slope, and then obtains the inductor current information by combining the HS and LS current slopes and the individual valley current information. Unlike the element 700 shown in FIG. 7, the current slope sensing element 800 is configured to sense the LS falling current slope information and the HS rising current slope information, and integrate the sensed information to obtain the inductor current information. Since a part of the element 800 for sensing the LS falling current slope is similar to the current slope element 700 shown in FIG. 7, detailed descriptions of the components for sensing the LS falling current slope information will not be repeated here, so as to avoid repetition.

Regarding the HS rising current slope, the switch SW1a is controlled by a signal LXrd, and the signal LXrd represents a sensing time of the rising current slope. The sensing time is equal to the on-time of the HS switch minus the trailing-edge blanking time. When the signal LXfd becomes high (that is, the inductor current rise time), the switch SW1a is turned on. The rising input voltage V _LX is differentiated by a differentiator. The differentiator includes a capacitor 710 and a transconductance amplifier _{720 a} . The transconductance amplifier 720 a is converted into a DC current slope value I _{SLP_R} . Then, the current slope information I _{SLP_R is} sampled and held in the sample and hold circuit ₇₃₀ a, and is converted into the current slope information I _{SLP_R} (n) in the n-th time. In this embodiment, since the sensing element is configured to sense the HS slope information, the LS slope information is not needed, and the rising slope calculator can obtain the HS slope information. Using the information of the falling current slope I _{SLP_F} (n), the rising current slope I _{SLP_R} (n) and the valley voltage information V _{SEN_VALLEY are sensed} from the voltage V =, and the switches SW2 and SW3 are controlled by the PWM signal, which helps to make the message and capacitor 750 is integrated to produce the output voltage V _SEN (n), as shown in Figure 7.

Although the present invention has been described in detail with respect to certain preferred versions, various modifications, variations and equivalents may exist. Therefore, the scope of the present invention should not be determined by the above description. On the contrary, the scope of the present invention should refer to the scope of the attached patent application and all equivalents thereof. Any option (preferred or not) can be combined with any other option (preferred or not). In the scope of patent application, unless specifically stated otherwise, the indefinite articles "a" or "an" refer to the number of one or more items in the following content. Unless the limited function is explicitly indicated by "meaning", the scope of the attached patent application should not be considered as a limitation of meaning-plus-function.

100, 200‧‧‧ system

105, 107‧‧‧ nodes

300‧‧‧ Inductive current sensing element

310‧‧‧LS Current Sensing Circuit

320‧‧‧Slope Sensing Circuit

330‧‧‧ Valley Current Sensing Circuit

340‧‧‧ Operation Circuit

342‧‧‧Subtraction circuit

350‧‧‧Current Slope Synthesis Circuit

352‧‧‧addition circuit

360‧‧‧Buffer Drive

402, 404, 406, 408, 410, 412, 414, 416, 422, 424, IMON, ISS, LXf, LXfd ‧‧‧ signals

418‧‧‧ signal, LS current slope information

420‧‧‧ signal, HS current slope information

500‧‧‧Buck DC-DC Converter

512‧‧‧ADC

520‧‧‧Digital Operator

530‧‧‧DAC

600‧‧‧Current slope sensing element

610, 650, 710, 750, C1, CS‧‧‧ capacitors

620, 900a‧‧‧ Differentiator

630‧‧‧Sampling and holding circuit

640‧‧‧Integrator

700‧‧‧ components

720‧‧‧ amplifier 730, 730a‧‧‧ sample and hold circuit

735‧‧‧ rising slope operation circuit

720a‧‧‧Transconductance Amplifier

ADC‧‧‧ Analog to Digital Converter

D1, D2‧‧‧ diodes

DAC‧‧‧ Digital to Analog Converter

GND‧‧‧ Ground

I _{HS_SLP} ‧‧‧HS current slope information

iL‧‧‧Current

_{LS_SLP} ‧‧‧LS current slope information

I _REF ‧‧‧DC offset

Is (n) ‧‧‧DC current slope information

I _{S_VALLEY} ‧‧‧ Valley current message

I _SLP ‧‧‧ Composite signal

I _{SLP_F ‧‧‧DC} current slope value

I _{SLP_F (n)} ‧‧‧ current slope information, falling current slope

I _{SLP_R ‧‧‧DC} current slope value, current slope information

I _{SLP_R (n)} ‧‧‧ current slope information, rising current slope

L1‧‧‧Inductor

M1‧‧‧HS switch

M2‧‧‧LS switch

PWM‧‧‧Pulse Width Modulation

RDC‧‧‧Resistor

RS‧‧‧ Resistor

SH1, SH2‧‧‧Trigger signal

SW1, SW1a, SW2, SW3‧‧‧ switches

V _CS , V _DS , V _LX ‧‧‧ Voltage

V _IN ‧‧‧ Input voltage

vin (t) ‧‧‧Input voltage signal

V _MON ‧‧‧Voltage signal

V _OUT 、 V _SEN 、 V _{SEN (n)} ‧‧‧ Output voltage

V _{SEN_vally} ‧‧‧ Valley voltage information

Figure 1 (a) shows a schematic diagram of a conventional SMPS with an inductive current sensing element;

Figure 1 (b) shows a signal waveform diagram in the SMPS shown in Figure 1 (a);

FIG. 2 is a schematic structural diagram of an SMPS system with an inductive current sensing element according to various aspects of the present invention;

FIG. 3 is a schematic structural diagram of an inductive current sensing element according to various aspects of the present invention;

FIG. 4 shows a signal waveform diagram of the inductor current sensing element shown in FIG. 3;

Figure 5 (a) shows a schematic structural diagram of a conventional SMPS;

Figure 5 (b) shows a signal waveform diagram in the SMPS shown in Figure 5 (a) with the conventional inductor current slope sensing element shown in Figure 5 (c);

FIG. 5 (c) is a schematic structural diagram of a conventional inductor current slope sensing element;

FIG. 6 (a) is a schematic structural diagram of an inductor current slope sensing element according to various aspects of the present invention;

FIG. 6 (b) shows a signal waveform diagram of the inductor current slope sensing element shown in FIG. 6 (a);

Figure 7 (a) illustrates a schematic diagram of an inductor current slope sensing element used in an SMPS system according to various aspects of the present invention;

FIG. 7 (b) shows a signal waveform diagram of the inductor current slope sensing element shown in FIG. 7 (a);

FIG. 8 is a schematic structural diagram of an inductor current slope sensing element used in an SMPS system according to various aspects of the present invention;

Figures 9 (a) and 9 (b) are schematic diagrams showing the structure of a differentiator arranged in the inductor current slope sensing element shown in Figure 6 (a).

Claims (34)

A switching power supply system includes: a switching power supply including: a high-end switch and a low-end switch coupled in series; and an output filter including an inductor and a capacitor coupled to the high-end switch and the A switch node in which a low-end switch is connected in series, wherein an inductor current is provided to a load by the inductor; and an inductor current sensing element is coupled to the low-end switch. The inductor current sensing element has: a first input Terminal for receiving a node signal indicating the voltage level at the switching node; a second input terminal for receiving an input voltage V _{IN of the system} ; and a third input terminal for receiving an output of the system Voltage V _OUT ; wherein the inductive current sensing element is configured to receive a first constant DC slope message, a second constant DC slope message and a first constant DC slope message according to the first input terminal, the second input terminal and the third input terminal. A valley current message, and generating an output signal according to the first constant DC slope message, the second constant DC slope message, and the valley current message, which The output signal having a triangular waveform, including a rising slope and a falling slope, proportional to the rising slope of the inductor current and the falling slope. The system according to item 1 of the patent application scope, wherein the inductive current sensing element comprises: a current sensing circuit that generates a sensing current according to a node message, wherein the sensing current includes a first current slope and A minimum current value; a slope sensing circuit coupled to the current sensing circuit, the slope sensing circuit having a first input terminal of the slope sensing circuit for receiving the sensing from the current sensing circuit Current, wherein the slope sensing circuit is configured to convert the first current slope in the sensing current into the first constant DC slope information; an arithmetic circuit coupled to the slope sensing circuit, the arithmetic circuit has: A first input terminal of an arithmetic circuit for receiving the first constant DC slope message from the slope sensing circuit; a second input terminal of the arithmetic circuit for receiving the input voltage V _IN ; and a third input of the arithmetic circuit terminal for receiving an output voltage V _OUT; wherein the calculation circuit according to a first, a second and a third input terminal of the operational circuit for generating the second DC constant slope News And a current slope synthesis circuit coupled to the operation circuit and an efficiency sensing circuit, the current slope synthesis circuit has: a first input end of the current slope synthesis circuit for receiving the first constant DC slope message; The second input terminal of the current slope synthesis circuit is used to receive the second constant DC slope information; and the third input terminal of the current slope synthesis circuit is used to receive a control signal; the current slope synthesis circuit is configured to configure the first And the second constant DC slope information are integrated, and a composite signal is generated according to the control signal, wherein the composite signal has a triangular waveform including the rising slope when the control signal is in a first state and when the control signal is at The falling slope in a second state opposite to the first state, wherein the rising slope and the falling slope of the composite signal are respectively proportional to the rising slope and the falling slope of the inductor current. The system according to item 2 of the scope of patent application, further comprising a valley current sensing circuit coupled to the current sensing circuit. The valley current sensing circuit has a first input terminal of the valley current sensing circuit. For receiving the sensing current from the current sensing circuit, wherein the valley current sensing circuit is configured to convert the smallest current value of the sensing current into the valley current message. According to the system described in item 3 of the scope of patent application, each of the slope sensing circuit and the valley current sensing circuit has a sample and hold circuit. The system according to item 2 of the scope of patent application, further comprising an adding circuit coupled to the current slope synthesizing circuit and a valley current sensing circuit, wherein the adding circuit is configured to combine the synthesized signal and the valley value The current message generates a combined signal. The system according to item 5 of the patent application scope, further comprising a buffer driver coupled to the addition circuit, wherein the buffer driver is configured to drive the combined signal from the addition circuit to generate the output signal. The system according to item 2 of the patent application range, wherein the arithmetic circuit is configured to generate the second constant DC slope by multiplying the first constant DC slope information by ((V _IN -V _OUT ) / V _OUT ) message. An inductive current sensing element is used to detect an inductive current in a switching power supply. The switching power supply has a high-end switch and a low-end switch connected in series, and an output filter. The output filter includes An inductor and a capacitor are coupled to a switching node through the high-side switch and the low-side switch, wherein the inductor current is provided to a load by the inductor, and the inductor current sensing element includes: a current sensing circuit, coupled To the low-end switch, the current sensing circuit is configured to sense the current on the low-end switch and generate a sensing current, wherein the sensing current includes a first current slope and a minimum current value; A slope sensing circuit is coupled to the current sensing circuit. The slope sensing circuit has a first input terminal for receiving the sensing current from the current sensing circuit. The slope sensing circuit is configured. To convert the first current slope in the sensing current into a first constant DC slope message; an operation circuit coupled to the slope sensing circuit, the operation Path having: a first input terminal of the operational circuit for receiving the first message from the constant current slope slope sensing circuit; a second input terminal for receiving an input of a SMPS voltage V _IN; a third An input terminal for receiving an output voltage V _{OUT of} the SMPS; the arithmetic circuit is configured to generate the second constant DC slope information according to the first input terminal, the second and third input terminals of the arithmetic circuit; and A current slope synthesis circuit is coupled to the operation circuit and the slope sensing circuit. The current slope synthesis circuit has a first input terminal of the current slope synthesis circuit for receiving the first constant DC slope information, and a current slope synthesis circuit. A second input terminal of the circuit for receiving the second constant DC slope information; a third input terminal of the current slope synthesis circuit for receiving a control signal; and a current slope buffer circuit configured to integrate the control signal according to the control signal First and second constant DC slope information to generate a composite signal, wherein the composite signal has a triangular waveform, including when the control signal A rising slope in a first state and a falling slope when the control signal is in a second state opposite to the first state, wherein the rising slope and the falling slope of the composite signal are respectively proportional to the inductance The rise and fall of the current. The component according to item 8 of the patent application scope, further comprising a valley current sensing circuit coupled to a path of a current trench, the valley current sensing circuit having a valley current sensing circuit first input Terminal for receiving the sensing current from the current sensing circuit, wherein the valley current sensing circuit is configured to convert the minimum current value of the sensing current into a valley current message. The component according to item 9 of the application, wherein each of the slope sensing circuit and the valley current sensing circuit has a sample and hold circuit. The component according to item 9 of the scope of patent application, further comprising an adding circuit coupled to the current slope synthesizing circuit and the valley current sensing circuit, wherein the adding circuit is configured to combine the synthesized signal and the valley value The current message generates a combined signal. The component according to item 11 of the patent application scope, further comprising a buffer driver coupled to the addition circuit, wherein the buffer driver is configured to drive the combined signal from the addition circuit to generate an output signal, wherein the output signal The triangular waveform includes the rising slope and the falling slope, which are proportional to the rising slope and the falling slope of the inductor current. The component described in item 8 of the scope of patent application, the arithmetic circuit is configured to generate the second constant DC by multiplying the first constant DC slope information by ((V _IN -V _OUT ) / V _OUT ) Slope information. A method for sensing an inductor current in a switching power supply, wherein the switching power supply has: a high-end switch and a low-end switch connected in series; and an output filter including an inductor And a capacitor coupled to a switching node formed by the high-end switch and the low-end switch, wherein the inductor current is provided to the load by the inductor, the method includes: by sensing the current on the low-end switch, Generating a sensing current, wherein the sensing current includes a first current slope and a minimum current value; converting the first current slope in the sensing current into a first constant DC slope message; according to the first constant A DC slope message, an input voltage V _IN of the switched-mode power supply and an output voltage V _{OUT of} the switched-mode power supply to generate a second constant DC slope message; and integrating the first and second signals according to a control signal Constant DC slope information to generate a composite signal, where the composite signal has a triangular waveform, including a rise when the control signal is in a first state The slope and a falling slope when the control signal is in a second state opposite to the first state, wherein the rising slope and the falling slope of the composite signal are respectively proportional to the rising slope and the falling slope of the inductor current. . The method according to item 14 of the patent application scope, further comprising converting the minimum current value in the sensing current into a valley current message. The method of claim 15, wherein the step of converting the minimum current value in the sensing current to the valley current message includes sampling and maintaining the minimum current value according to a trigger signal. The method according to item 14 of the patent application scope, wherein the step of converting a first current slope in the sensing current into the first constant DC slope information includes sampling and holding the first current according to a trigger signal Slope. The method according to item 15 of the patent application scope further comprises generating a combined signal by combining the synthesized signal and the valley current information. The method according to item 14 of the scope of patent application, wherein the step of generating the second constant DC slope information includes multiplying the first constant DC slope information by ((V _IN -V _OUT ) / V _OUT ). A slope sensing element is used for sensing the slope of an input signal and providing an output signal proportional to the input signal. The slope sensing element includes: a differentiator having an input terminal for receiving a signal having a triangle The input signal of the waveform has at least one slope, wherein the differentiator is configured to use a first capacitor to generate a differential signal by differentiating the input signal; a sample and hold circuit having: a first input terminal, A second input terminal for receiving a trigger signal; wherein the sample-and-hold circuit is configured to sample and hold the differential signal when the trigger signal is turned on to generate the differential signal Converted into a constant DC slope message; and an integrator having an input terminal for receiving the constant DC slope message, wherein the integrator is used for receiving the output signal, using a second capacitor, and the waveform of the output signal is proportional to the The waveform of the input signal. The component as claimed in claim 20, wherein the differentiator comprises an operational coaching amplifier. The component according to claim 20, wherein the integrator is configured to generate the output signal by charging and discharging the second capacitor according to the constant DC slope information. The component according to item 20 of the patent application scope further includes an arithmetic circuit coupled to the sample and hold circuit, and the arithmetic circuit is configured to generate a second constant DC slope message according to the constant DC slope message. The component according to item 23 of the application, wherein the integrator has a second input terminal for receiving the second constant DC slope information, and the integrator is configured to use the second capacitor, The output signal is generated to integrate the constant DC slope information and the second constant DC slope information. The element as described in claim 24, wherein the integrator includes two switches controlled by a control signal, and when the control signal is in a first state, a first switch is turned on and a second switch Off; when the control signal is in a second state opposite to the first state, the first switch is turned off and the second switch is turned on; wherein when the control signal is in the first state, according to the constant The DC slope information causes the second capacitor to discharge; when the control signal is in the second state, the second capacitor is charged according to the second constant DC slope information. The component according to item 20 of the patent application scope, further comprising a second differentiator for generating a second differential signal by using a first capacitor; and a second sample and hold circuit for converting the second differential signal Into a second constant DC slope message. The component according to claim 26, wherein the integrator has a second input terminal for receiving the second constant DC slope; wherein the integrator is configured to use a second capacitor to generate the output signal, In order to integrate the constant DC slope information and the second constant DC slope information. The component as described in claim 27, wherein the integrator includes two switches controlled by a control signal, and when the control signal is in a first state, a first switch is turned on and a second switch Off; when the control signal is in a second state opposite to the first state, the first switch is turned off and the second switch is turned on; wherein when the control signal is in the first state, according to the constant The DC slope information causes the second capacitor to discharge; when the control signal is in the second state, the second capacitor is charged according to the second constant DC slope information. A method for sensing the slope of an input signal and providing an output signal proportional to the input signal includes: differentiating an input signal having a triangular waveform with at least one slope, and generating a differential signal by using a first capacitor; When a trigger signal is turned on, the differential signal is sampled and held to convert the differential signal into a constant DC slope message; and a second capacitor is used to generate an output signal to integrate the constant DC slope message, wherein the output The waveform of the signal is proportional to the waveform of the input signal. The method of claim 29, wherein the step of generating the output signal includes charging and discharging the second capacitor based on the constant DC slope. The method according to item 29 of the patent application scope, further comprising generating a second constant DC slope information according to the constant DC slope information. The method as described in claim 31, wherein the step of generating the output signal by using the second capacitor includes, when a control signal is in a first state, according to the constant DC slope information, the second capacitor is Discharging; and when the control signal is in a second state opposite to the first state, charging the second capacitor according to the second constant DC slope message. The method according to item 29 of the patent application scope, further comprising using the first capacitor to generate a second differential signal, and converting the second differential signal into a second constant DC slope message. The method of claim 33, wherein the step of generating the output signal by using the second capacitor includes, when a control signal is in a first state, according to the constant DC slope information, the second capacitor is Discharging; and when the control signal is in a second state opposite to the first state, charging the second capacitor according to the second constant DC slope message.